MDEV-37098 Fix Spider test failures in network-less environments

When running tests in environments without a network interface (e.g.
Podman container launched with `--network=none`), Spider was not able to
retrieve a hardware address to generate a node ID. This triggered a
warning in the server log, causing MTR to fail multiple Spider tests due
to unexpected warnings and output result mismatches with:

    [Warning] mariadbd: Can't get hardware address with error 2

Fix this by logging Spider hardware address errors to server log only
by setting it as a NOTE. This does not pollute the client output.

When`my_gethwaddr` fails, the code zeroes out the address buffer,
resulting in a `spider_unique_id` formatted like `-000000000000-PID-`,
which is fully valid and emitting warnings was a bit overkill to begin
with.

Author: ottok

storage/spider/spd_table.cc

@@ -6288,8 +6288,12 @@ int spider_db_init(
 
   if (my_gethwaddr((uchar *) addr))
   {
-    my_printf_error(ER_SPIDER_CANT_NUM, ER_SPIDER_CANT_STR1, MYF(ME_WARNING),
+    my_printf_error(ER_SPIDER_CANT_NUM, ER_SPIDER_CANT_STR1, MYF(ME_NOTE),
       "get hardware address with error ", errno);
+    /*
+      If we can't get the hardware address, we zero it out.
+      The spider_unique_id will then look like: -000000000000-PID-
+    */
     bzero(addr,6);
   }
   spider_unique_id.str = spider_unique_id_buf;